Stability of optical reorientation of nematic liquid crystals doped with azo-dyes in polymer networks

We report on the stability of the optical reorientation of doped nematic liquid crystals (LCs) with azo-dyes in polymer networks. The photo-reactive polymer networks formed within the doped LC medium play a critical role in achieving the stable optical reorientation of the LC originating from the trans-cis transformation of the dye molecules. Moreover, the photo-reactive polymer layer on the substrate surface is required to produce the surface memory effect of the dye-doped LC. The optically induced memory is well retained in the dye-doped LC only in the presence of the polymer network medium.